java threading issue , final for each: XX:+UseCriticalJavaThreadPriority would solve this in a majority of cases. RedNumberz fixes that would work for your PC is changing java priority to higher(or reducing background operations).
here is the actual bug info so if it doesn't fix or you want to know more: <a href="<a href=" https:="" bugs.mojang.com="" browse="" mc-1794?filter="20315"">https://bugs.mojang.com/browse/MC-1794?filter=20315</a>